It was already a large A-arm because of the solidly bolted connection to the lower arm.

Part of me is worried about the limit on all the factory parts since I don't know it. Even chopping the OEM rotors off the hubs I was amazed at how easily the cast iron cut. It made me start to worry about them too. I ran a quick analysis on the hubs assuming it was a basic cast iron alloy. With 100% load transfer in the front and 1g of cornering acceleration on a 27" tall tire they should be close to failure. Not knowing the actual material is a big issue in figuring out how strong things are.

When I cut the threads in the radius rods the material felt good. It felt like a high quality steel. Not as gummy as a 41xx series but I'm sure it was at least a basic structural alloy similar to something like A36. I feel confident in the rods. The factory thread is a 5/8 course thread. The minor diameter on that thread would be the failure point of the rod when in tension. We are re-cutting a 3/4" fine thread which barely removes any material compared to the factory thread.

New tire compounds change everything. The way I toss my 4000lbs around, I'm just waiting for the next component to break even if it's just a completely unaltered OEM part. I'm only getting stickier with the tires so we will see.

Sort of off topic, when I replaced all my front bushings with urethane, I also replaced the strut rod bushings. What I did not do was torque them down all the way. I noticed that at the same torque spec, the urethane hardly moved, so yeah, there is pressure on the rod. Back off the bolt and it still keeps everything tight, but allows the rod to move. Acts much more like the rubber. I am sure there is a durometer/squish/torque relationship here, but I am but a humble IT guy, not a Materials Engineer.

Sort of off topic, when I replaced all my front bushings with urethane, I also replaced the strut rod bushings. What I did not do was torque them down all the way. I noticed that at the same torque spec, the urethane hardly moved, so yeah, there is pressure on the rod. Back off the bolt and it still keeps everything tight, but allows the rod to move. Acts much more like the rubber. I am sure there is a durometer/squish/torque relationship here, but I am but a humble IT guy, not a Materials Engineer.

I think the general consensus was with stock strut rods your best to stick with rubber bushings. There have been some reported incidents of stock strut rods breaking with urethane bushings since they were designed to work with flexible rubber bushings.

I've had some email correspondence with Leslie/Eric and littleshopmfg.com

They are willing to fab an adjustable strut arm if we can get 8 peeps together to order. Anyone interested? I'm ready.

I'd be happy to produce this part if you could get at least 8 people committed to purchasing it. Lots of people asking/wanting it but no one has set up something to make it happen. If you want to organize that, I'd be fine with the manufacturing side of it.

I'd actually be interested just not now. All my cash is going into my motor and trans next. Once that's done, I'd commit with a deposit if necessary. Even though I want my car to appear basically stock, I think this would be a subtle and worthwhile upgrade to ensure that the suspension geometry stays put.

There are a few different designs floating around now. I'd be interested to see what design is chosen for a small run. Any ideas?

I count 3 bolt on options.

Global West wrote:

RRS wrote:

cggrob wrote:

I personally like how easy the RRS is.

I was kinda playing with a similar design for our stock rods. Like this..

Obviously with a spacer between the bearing and the seat that the washer usually sits. I left out all the hardware and stuff too. The caster is adjusted by swapping spacers. This could be very cost effective and a totally bolt-on affair. I just don't like axial load on sphiricals but using a safe number of 15% radial load limit for the axial load limit, a bearing to fit this application wouldn't be anything exotic. The rod is weak in comparison. The only reason I didn't do this is because I don't think the rod is strong enough for what I am doing around that 5/8 thread and of course the axial loading issues.

I think the heim bearing option looks good especially if they fabricate a better strut rod to go with it. Its proven, easy to maintain, easy to get parts to replace the rod end if needed.

I'm thinking that you don't see that much axial load on that strut arm. Its the suspension compression and forces from a bump from something like a pothole that would shock the arm. If you can figure out the loading with the suspension compressed and the shock load from the lower control arm pulling on the rod while the suspension is compressed that may be the max load you'll see.

I have no way to know for sure. Your guess is better than mine.

So far we only have 2-3 people interested in a group buy for an adjustable strut-arm. Is there anyone else to contact that would be interested? We need 8 people to sign up.

You believe the rubber bushings absorb much of the shock if the wheel gets hit hard. When you go to the hard mount strut rod your concerned that the rod itself may be a failure item because its not designed to take that shock at the threaded end near the bushing?

I guess its worth looking at the mustang rods from the likes of Total Control Products, CPP, etc. and find out what material they used (prolly chromoly tubing) and the size of the rod to get an idea of the shock load they designed it for...just a thought for a reference.

You believe the rubber bushings absorb much of the shock if the wheel gets hit hard. When you go to the hard mount strut rod your concerned that the rod itself may be a failure item because its not designed to take that shock at the threaded end near the bushing?

Yes, this is why I believe some have seen strut rod failure with urethane bushings. When Ford engineered this suspension, they wanted the lower control arm to move fore and aft with road impacts. The rubber cushioning of the strut rod allow for this. Remember most suspensions from this era were primarily designed for smooth ride first.

That said, a properly engineered rod will ensure the lower control arm will always be in the correct position and ensure that suspension geometry is maintained under all conditions, at perhaps a slight increase in ride harshness. I think looking at the Mustang rods is a good start. I wonder though if the Torino's have more load on their arms due to the great weight and the spring being on the LCA?

I think the shock/load from an impact would be the same regardless of the vehicle weight. for simplicity, assume the vehicle mass absorbs a negligible amount relative to the wheel shock of an impact from a pot hole (for example). Just thinking about simple vectors of the car forward motion vs the mass of the wheel/suspension.

I think the poly bushing failure mode is more complex. I'm thinking its also the repeated up/down motion of the wheel levering on the bushing which is more rigid due to the "hardness" of the poly bushing. All the pics from the Mustangs and other cars with this suspension show the breakage occurs right at the threads near the nut. Its as if the arm is prying up/down near the nut until the metal fatigues (over time and usage) until it fractures.

I've had some email correspondence with Leslie/Eric and littleshopmfg.com

They are willing to fab an adjustable strut arm if we can get 8 peeps together to order. Anyone interested? I'm ready.

I'd be happy to produce this part if you could get at least 8 people committed to purchasing it. Lots of people asking/wanting it but no one has set up something to make it happen. If you want to organize that, I'd be fine with the manufacturing side of it.

My understanding is they are new strut rods. I've asked the question and awaiting the response. It would be a bad idea for a company to produce anything but a new rod just for liability reasons unless they dont require any mods to the OEM rods.

I think the shock/load from an impact would be the same regardless of the vehicle weight. for simplicity, assume the vehicle mass absorbs a negligible amount relative to the wheel shock of an impact from a pot hole (for example). Just thinking about simple vectors of the car forward motion vs the mass of the wheel/suspension.

I think the poly bushing failure mode is more complex. I'm thinking its also the repeated up/down motion of the wheel levering on the bushing which is more rigid due to the "hardness" of the poly bushing. All the pics from the Mustangs and other cars with this suspension show the breakage occurs right at the threads near the nut. Its as if the arm is prying up/down near the nut until the metal fatigues (over time and usage) until it fractures.

I still figure that a 4000 lb car will hit a pot hole with more force than a 3000 lb car, and this force will be carried through the front suspension...

You're right about the poly bushing failure though, the up and down motion would likely have more on a fatiguing factor on the strut rods than the fore and aft. But bottom line is that the factory rods were never intended to be used with an inflexible joint that the poly bushings create.

I hope you guys are able to get enough interest in these rods....I just wish I had the cash to commit now.

I think the shock/load from an impact would be the same regardless of the vehicle weight. for simplicity, assume the vehicle mass absorbs a negligible amount relative to the wheel shock of an impact from a pot hole (for example). Just thinking about simple vectors of the car forward motion vs the mass of the wheel/suspension.

I think the poly bushing failure mode is more complex. I'm thinking its also the repeated up/down motion of the wheel levering on the bushing which is more rigid due to the "hardness" of the poly bushing. All the pics from the Mustangs and other cars with this suspension show the breakage occurs right at the threads near the nut. Its as if the arm is prying up/down near the nut until the metal fatigues (over time and usage) until it fractures.

It's a bit of both, the impact shock and the flex at the same moment. It's not just the up-and-down as the strut rod also keeps the LCA from moving front-to-back as it goes up-and-down. Stiffening the bushing means the rod flexes at the bushing, instead of the bushing flexing, and the threaded area is where it focuses the stress.

The picture I posted above of the nascar suspension still uses bushings, but the rods are heavier, and they used BIG sleeves for adjustment.

If I was going to use a stiffer bushing, I wouldn't want the strut rod necked down where the threads are.

I would like to see how the Global West design works in the real world, the RRS design seems like it would be good as well. I just wonder where these designs will move the "Fail-point" to.

Edited by Big Bird - 04-September-2015 at 2:31PM

"What we do in full frontal view, is more honest than your cleaned-up mind."Randy1979 T-Bird 2005 F-150 STX RCSB 4.6, 3.55 LSD How the Heck does a REGULAR CAB SHORTBED weigh over 5200 pounds?

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